A Hamptons man bilked his father out of $​300,000 by claiming to invest it with a “financial “genius” pal when he actually used it to pay liens ​and other debts ​on his Southampton ​– and then sold the home for $1.5 million, ​the dad charges in a new federal lawsuit​ against his son​.

Dr. Robert Schwartz, 76, of Arizona, claims that his son, Richard Schwartz, 42, called him in February and told him that he was strapped for cash and needed $150,000 loan.

The elder Schwartz, a retired dermatologist, agreed to give him $100,000 to help him with his finances, according to Long Island court papers.

But the son​, a securities trader ​, coaxed an additional $200,000 out of his father by telling him that he was working with a finance guru who was turning 24 percent profits annually with masterful investments, according to the suit.

The ailing father ​– who suffered a major stroke five years ago and several ​since ​– eventually sent his son a total of $300,000 with $200,000 of it intended for investment with the purported financier, according to the suit.

But the father claims that Schwartz eventually admitted in May that he used all of the dough to pay off large liens and missed mortgage payments on his Canoe Place Road home in Southampton that he shares with his wife and three kids.

The father claims that he found out his son put up the home for sale in June and records show that it was sold in recent months for $1.5 million.

”He further advised him that he had spent all, or a significant portion, of these funds to remove liens and make past due mortgage payments on his home located at 360 Canoe Place Road in Southampton, New York,” the suit states.

Records show that the son owed a Suffolk County tax warrant of $1,727 in January that was cleared in April.

Dr. Schwartz filed suit against his son for $300,000 to “remedy Richard’s conduct in fraudulently misappropriating $300,000 in assets from his father and using those assets, in whole or in part, to clear title to his home in Southampton, New York, so that he could place the home on the market for sale.”

Records show that Richard Schwartz once owned an Upper East Side apartment and the suit refers to him as an unemployed stock trader.

He did not immediately return a call for comment and the attorney for his father did not respond to a message for comment.